sprue plate adjustment

Hi Al
I just read your tips on adjusting  your sprue plates and was wondering, is this adjustment made on a cold mold or one that is up to casting temp. I have seen comments on both ways. The theory was that when it’s made cold, the blocks would expand when up to temp and cause the adjustment to be tighter  than it should and cause sprue plate/block galling.
Thanks for a great product, service and now a forum.